void main(){
  //常量构造方法(构造函数用const修饰，所有属性用final修饰)
  const person=const Person('tony', 41, 'male');
  person.work();
}

class Person{
  final String name;
  final int age;

  final String gender;
  const Person(this.name,this.age,this.gender);
  void work(){
    print('Working.....');
  }
}